In the coming year, the relationship between cell-mediated immune responses measured in vitro and disease in vivo will be examined using immunologic deprivation of the mouse followed by reconstitution with specific cell types in order to answer the following questions. 1) Will immune T cells which are the most potent killer cell in vitro (or non-immune T cells which are inactive) alter the pathogenesis or rabies virus in the mouse. 2) What is the contribution to rabies virus pathogenesis of antibody-dependent cellular cytotoxicity (ADCC) as measured in vitro and as mediated by either the macrophage coated with cytophilic antibody or the k cell. In each case, changes in pathogenesis will be measured by clinical signs, histopathologic changes and virus titers. The following characterization of antibody will be completed. 1) What are the affinity and avidity characteristics of antibody which: a) is protective to the mouse when administered immediately before or shortly after infection; b) induces early death when given at a later time after infection; c) mediates ADCC in vitro.